1. Field of the Invention
This invention resides in the field of laboratory apparatus for electroporation. In particular, this invention concerns the construction of the shocking chamber in which biological cells suspended in the appropriate media are exposed to the high-voltage electrical pulses that are used in electroporation.
2. Description of the Prior Art
Electroporation, also known as transfection, is a process by which a biological cell is exposed to a high-voltage electric potential to create transitory pores in the cell membrane that re-close when the potential is removed. The pores allow large molecules such as nucleic acids and proteins to enter the cell from the cell suspension medium, and electroporation is therefore a means of infusing the cells with these molecules. Electroporation is particularly useful in placing foreign DNA inside living cells, thereby enabling the cells to express desirable proteins or to otherwise behave in a specified manner dictated by the infused DNA.
The amount of voltage used in electroporation depends on the cell type and the species being infused. Smaller cells, for example, tend to require higher field strengths, as do larger molecules, and voltages can range from as low as 200 V/cm to as high as 35,000 V/cm. With voltages of this magnitude, user safety is a concern.
An electroporation apparatus typically includes a cuvette to hold the cell suspension and a shocking chamber in which the cuvette is inserted and the voltage applied. The cuvette is generally inserted into the chamber by way of a slide. This requires two hands and entails a certain degree of awkwardness and hence risk on the part of the user.
The present invention resides in a shocking chamber which includes a base and a hinged lid, the chamber designed to receive and fully enclose a cuvette and containing electric circuitry arranged to impose high voltage across the cuvette once the cuvette is inserted in the chamber, the circuitry further arranged to engage a high-voltage power source upon simple closing of the lid and to disengage the power source upon opening of the lid, both of which can be done by a simple one-hand operation. The base contains two pairs of electrical leads, one pair engaging the cuvette with spring-loaded contacts that both provide electrical connections to the cuvette and secure the cuvette to the base of the chamber, and the other pair joined to high-voltage terminals on the chamber exterior. The engagement and disengagement of the power source to the cuvette is achieved by a shunt built into the lid. The shunt bridges the two pairs of leads in the base when the lid is closed and pivots out of the way to clear all leads when the lid is opened. In preferred embodiments of the invention, each of the four electric leads in the base has a hook-shaped end extending upward toward the lid so that the shunt contacts engage the hooks for a secure connection. In further preferred embodiments, the chamber contains electrically insulating partitions separating each of the electrical leads to avoid arcing and inadvertent finger contact by, and injury to, the user.
Further features, advantages, and preferred embodiments of the invention will be apparent from the description that follows.